1. Field of the Invention
This invention relates to winding apparatus and, more particularly but not exclusively, is concerned with winding apparatus for winding wire.
2. Description of the Prior Art
One known type of wire winding apparatus includes means for supporting and rotating a flanged spool, a wire guide arranged to traverse the wire back and forth lengthwise of the spool in use, and two end sensors operative to automatically reverse the direction of operation of the guide at the end of each traverse. Such apparatus is that herein referred to as being "of the type described." The intention is that when the end sensors are correctly positioned the wire forms a substantially uniform winding between the flanges of the spool.
In practice it has been found that the distance between the flanges of different spools differs, and that the distance between the flanges of the same spool can vary due to, e.g., mishandling of the spool. Furthermore, it is not always possible to ensure that different spools are held in exactly the same position in the same apparatus. Because of these factors one spool may be satisfactorily wound with the end sensors in one position while another spool has an accumulation or deficiency of wire (as hereinafter explained) adjacent one or both flanges with the end sensors in exactly the same position.
In an effort to achieve consistently uniform windings, apparatus has been constructed which includes means which detect accumulations or deficiencies of wire adjacent the flanges of a spool. If an accumulation is detected adjacent one flange a servo-motor is actuated to move the end sensor associated with that flange toward the other end sensor by a fixed distance, thereby decreasing the traverse of the wire guide. If a deficiency is detected adjacent one flange the servo-motor is actuated to move the end sensor associated with that flange away from the other end sensor by the same fixed amount.
Different means have been employed for detecting an accumulation or deficiency of wire. One such means directly detects an accumulation or a deficiency by sensing the angle between two arms carrying respective rollers which run on the surface of the wire on the spool, one adjacent a flange and the other some distance from it. Another such means indirectly detects an accumulation or a deficiency by sensing, e.g., photoelectrically, a rise or a fall in the path of movement of the wire as it approaches each flange, or by sensing changes in the tension of the wire as it approaches the flange. However, none of these detecting means so far proposed has been able to deal satisfactorily with a situation that often arises in which both an accumulation and a deficiency of wire appear next to one another adjacent a flange. In such a situation an indirect detecting means may fail to detect, for example, a deficiency which appears immediately adjacent the flange and immediately outwardly of an accumulation, particularly if the associated end sensor is currently aligned with a point between the deficiency and the accumulation. Similarly a direct detecting means may, in the circumstances just mentioned, react to the deficiency whereas it would more advantageously have reacted to the accumulation.